docs: def _subviews_from_utterance_splits(self, splits):
          """
          Create subviews from a dict containing utterance-ids for each subview.
  
          e.g. {'train': ['utt-1', 'utt-2'], 'test': [...], ...}
          """
          subviews = {}
  
          for idx, subview_utterances in splits.items():
              filter = subview.MatchingUtteranceIdxFilter(utterance_idxs=subview_utterances)
              split = subview.Subview(self.corpus, filter_criteria=filter)
              subviews[idx] = split
  
          return subviews